Wife to hubby:
darling...
in pictures of shiva-parvathi, shiva has a trishool...
in vishnu-lakshmi: there's sudarshan chakra...
in ram-sita: bow & arrows...
but in krishna-radha picture krishna holds a flute... why?
hubby:
it's simple honey...
the three gods you mentioned first are with their wives...
that's why they have weapons...
krishna is with his girlfriend...
so no weapons! :p